Device for starting internal combustion engines



July 1 1969 CARL-GUSTAV s. JOHANSSON 3,456,121

DEVICE FOR STARTING INTERNAL COMBUSTION ENGINES Filed Dec. 8, 1966 Fig.7

\ l l g Era i 8/ 7 United States Patent U.S. Cl. 29038 8 Claims ABSTRACT OF THE DISCLOSURE Means for automatically starting an internal combustion engine of a car having a charging generator, an ignition circuit, and a starting relay with a thermostat adapted at a certain predetermined temperature of the engine to close said ignition circuit, and at a higher temperature to interrupt said circuit. A second circuit and a coupling relay adapted to close the second circuit. The starting relay is coupled in the second circuit and the second circuit is parallel to the ignition circuit. The coupling relay is connected between the thermostat and the chassis of the car. Means are provided which upon exceeding a certain number of revolutions of the engine reduce the energizing of the coupling relay to such an extent that the relay will fall. A contact is coupled in series with the coupling relay which is normally closed but adapted to interrupt when the engine is started. A relay coil is adapted to influence the contact and a transistor is controlled by the pulses from the ignition circuit with the relay coil coupled in series with the transistor.

The present invention has reference to a device of an automatic starting of internal combustion engines provided with a charging generator and a starting relay, in particular engines for vehicles provided with a thermostat which is adapted, at a certain temperature of the engine, e.g. 60 C., to close the ignition circuit of the engine and at another higher temperature, e.g. 80 C., to cut off this circuit. The main feature of the invention is to be seen therein that a coupling relay for closing the current circuit in which the starting relay is coupled and which is parallel to the ignition circuit, is coupled between the thermostat and the chassis of the car and that means are arranged, at the exceeding of a certain number of revolutions of the engine, to reduce the energizing of the coupling relay to such a degree that the relay falls.

The invention will now be elucidated with reference had to the attached drawing. In the drawing:

FIGS. 1 and 2 show coupling diagrams of two different embodiments of the start device according to the invention.

In FIG. 1 reference letter 1 denotes the thermostat which interrupts at a certain maxi-mum temperature of the engine, e.g. 80 C., and closes at a certain minimum temperature, e.g. 60 C. (or at corresponding temperatures in the coup of the car in which the engine is arranged) and a coupling relay has been denoted with 2, its closing contact with 3 and another relay with 4 and the disconnecting switch of this relay with 5, a transistor with 6, a resistance with 7, a condenser with 8 and a diode with 9, a voltage limiting diode with 10 and a condenser with 11. In FIG. 2 a thermostat has been denoted with La closing switch to the start relay with 3 and the two solenoids of the coupling relay with 12 and 13, respectively, a diode with 14 and another diode with 15.

Patented July 15, 1969 FIGURE 1 The battery voltage reaches via the thermostat 1 the relay coil 2 which via the switch 5 is connected to the negative pole of the car battery. The relay coil 2 influences the contact 3 which is coupled between the battery and the starting relay of the engine. From the thermostat 1 there extends also a connection to the ignition system of the car and to the relay coil 4 the other side of which via the transistor '6 is connected to the negative pole. A resistance 7 and a condenser 8 are connected between the base and emitter of the transistor. A connection extends from the breaker points of the current distribuor via the condenser 11 and the diode 9 to the base of the transistor. Between the condenser 11 and the doide 9 which are coupled in series, and earth there is connected the diode 10 limiting the voltage, this diode 10 taking the shape e.g. of a Zenerdiode.

FIGURE 2 From the thermostat 1 there extends a connection to the ignition system of the car. Current is fed from the thermostat 1 via a diode 15 through the relay coil 12 to earth. Between the generator of the car and earth there is connected a relay coil 13. The relay coils 12 and 13 are orientated in such a way that their magnet fields counteract each other. Between the generator of the car and the relay coil 12 there is coupled a diode 14.

FIGURE 1 When the engine has reached such a temperature that the thermostat 1 closes, the ignition system of the car is fed with voltage. Further, a current streams through the relay coil 2 via the contact 5 to earth. The relay coil 2 will then close the contact 3 whereas the starting relay of the engine and the start of the engine will begin to function. When the engine stands still, the transistor 6 is completely closed so that any current cannot pass through the relay coil 4. When the engine has started, positive voltage pulses will pass from the breaker points of the current distributor to the condenser 11. Here these pulses will be formed in such a way that the pulse time will be very short. The diode 10 limiting the voltage will ensure that all the pulses will be given the same voltage. The pulses charge the condenser 8 via the diodes 9. The diode 9 prevents the discharge of the condenser 8 via the current distributor. At sufficiently short pulse intervals, i.e. the engine has reached a cetrain number of revolutions, the resulting voltage over the condenser 8 will be so high that the transistor 6 opens and a current will go from the thermostat 1 through the relay coil 4 and the transistor 6 to earth. Hereby the contact 5 opens which cuts oh the cur-rent through the relay coil 2 so that the contact 3 opens. The current can then no more pass from the positive voltage to the starting relay, and the engine will therefore stop. A resistance 7 is coupled betwen the base and the emitter of the transisor 6 so as o prevent any remaining charge on the condenser 8 to open the transistor 6 when the engine has stopped.

FIGURE 2 A current is fed from the thermostat 1 via the diode 15 through the relay coil 12 to earth which causes the contact 3 to be closed whereas current will go from the positive pole to the starting relay of the car. When the engine starts, its generator will deliver a voltage and current will go from the coil 13 to earth. Since the relay coils 12 and 13 are identical but their magnet fields are directed 0pposite each other, the contact 3 will again be disconnected whereby the starting relay and the start of the engine of the car are disconnected. When the thermostat 1 is disconnected but the engine is driven in the usual manner, a current will pass from the generator through the relay coil 13 to earth. To prevent the relay contact 3 from closing a current is allowed to stream from the generator to the rest of the system of the car via the thermostat of the ignition sysem and a diode 15 is connected between the thermostat 1 and the relay coil 12 which blocks the current which thus cannot stream in the wrong direction.

The disconnection of the starting relay has been shown as taking place by means of electric coupling means but the disconnection may according to the invention be carried out by means of purely mechanical means so that depending of the number of revolutions of the combustion engine or the charging generator, a disconnection on the starting relay will take place at reaching a certain predetermined number of revolutions.

What I claim is:

1. Means for automatically starting an internal combustion engine of a car having a charging generator, an ignition circuit, and a starting relay comprising a thermostat adapted at a certain predetermined temperature of the engine to close said igniion circuit and at a higher temperature to interrupt said circuit, a second circuit, a coupling relay adapted to close said second circuit, said starting relay being coupled in said second circuit, said second circuit being parallel to said ignition circuit, said coupling relay being connected between said thermostat and the chassis of the car, means upon exceeding a certain number of revolutions of the engine reducing the energizing of said coupling relay to such an extent that the relay will fall, a contact coupled in series with said coupling relay, said contact being normally closed but adapted to interrupt when the engine is started, a relay coil adapted to influence said contact, a transistor controlled by the pulses from said ignition circuit, said relay coil being coupled in series with said transistor.

2. Means as claimed in claim 1 wherein the base voltage of said transistor is directly proportional to the number of revolutions of the engine and via a diode and a condenser is connected to the breaker points of the ignition system, a condenser and a resistance being connected between said base and emitter.

3. Means as claimed in claim 2 wherein a diode for limiting the voltage is connected between said condenser and said diode is connected to earth.

4. Means as claimed in claim 2 wherein a Zener-diode for limiting the voltage is connected between said condenser and said diode, said Zener-diode being connected to earth.

5. Means as claimed in claim 1 wherein said coupling relay is provided with two identical coils, one of said coils being coupledbetween said thermostat and earth and the other one of said coils being coupled between the generator of the car and earth, said coils being polarized in such a way that their magnetic fields have opposite directions.

'6. Means as claimed in claim 5 wherein a diode is connected between the generator of the car and one of said coils.

7. Means as claimed in claim 5 wherein a diode is connected in series with said thermostat before one of said coils.

8. Means as claimed in claim 5 wherein a diode is connected between the generator of the car and one of said coils and a second diode is connected in series with said thermostat before one of said coils.

References Cited UNITED STATES PATENTS 7/1961 Boucher 290-38 4/1966 Fried 29038 

